Since product counterfeiting, product adulteration, unauthorized distribution and sale of products as well as false liability based on product substitution are major problems for manufacturers, it is important to identify the origin or the grade quality of fluid products like working/functional fluids during storage, transportation, distribution and in use. Working/functional fluids comprise engine oils, petroleum products, aqueous urea solutions (like AUS32), heat transfer fluids, transmission and hydraulic fluids, metalworking fluids, dielectric fluids.
Branded products i.e. lubricating oils or petroleum fuels can be tampered by dilution with lower or unspecified grade products. Consumers who are willing to pay more money for their expensive equipment or machine may lose their belief for the reputation of branded products, if product they buy has been counterfeited or adulterated. These adulterations result in lower performance of the equipment/machine in which these working/functional fluids are used.
There is also a need, for example, in case of an accident to identify the origin of the leaking or spilling fluid products from an unknown source to understand and evaluate their environmental risks. Furthermore, the source of the spill or leak may be identified and responsible parties should be fined for the act.
It is known that there is a strong request from the manufacturers to use tagging material for identification of the various fluid products for example, petroleum based hydrocarbon products. Tagging may help to trace the identity of fluids, and to identify various grades, and to distinguish manufacturer's brand in order to prevent any product adulteration.
It is common to use tagging materials or markers for variety of fluid products for example petrol based hydrocarbon products, in the form of dyes or colorants. Since these products have high absorption and/or fluorescence in the region of spectrum below 600 nm, it may be preferred to use tagging material or marker absorbing and/or fluorescing above 600 nm.
U.S. Pat. No. 5,928,954 discloses a method for tagging petroleum based hydrocarbon products, such as gasoline, diesel, heating oil, lubricating oil or crude petroleum. A small amount of a fluorescent dye (0.01-1000 ppm by weight) is blended as a marker with petroleum based hydrocarbon products. The presence of the marker in the products is subsequently determined by the excitation of the fluorescent dye and detection of its emission at a dye-specific wavelength, preferably between 630-830 nm. Each and every dye needed to be excited at a different wavelength.
U.S. Pat. No. 5,525,516 describes a method for imparting invisible markers to petroleum based hydrocarbon products for identification purposes. The near infrared emitting fluorophores at low levels are added to petroleum based hydrocarbon products as markers and detected by exposing the marked product compositions to near infrared radiation having a wavelength in the 670-850 nm range and then detecting the emitted fluorescent light via near infrared light detection means.
U.S. Pat. No. 6,274,381 discloses a method for the identification of petroleum based hydrocarbon products tagged with one or more visible dyes with absorption maximum between 500-700 nm at a level less than 1 ppm and detecting the presence of the dyes upon exposing them to radiation between these wavelengths and recording the absorption of dyes and quantifying their concentration based on absorption amounts with a detection equipment sensitive in this spectral region.
WO 2009 120563 A1 describes a method using a marker in a functional fluid, employed in the variety of automotive, off-highway vehicles, on-highway vehicles, equipment, machines, metal working and industrial applications, which survives during the use of the functional fluid in an application with a reagent solution to identify the functional fluid rapidly either before, during or after the functional fluid's use and which is a suitable method for the identification of a functional fluid in the field. A sample of the marked functional fluid before, during or after the fluid's use is obtained, said sample and a reagent solution are placed on a test medium such that they are in contact with each other and the marker in the functional fluid sample is reacted with the reagent solution on the test medium to produce a visible change. Then the resultant visible change is determined and compared with the original functional fluid. Selected marker substances can be one of diazo dyes, anthraquinone dyes, phthalein dyes, and the like, metals, metal salts, metal oxides, metal coordination complexes and the like.
Patent application US2005/0260764 A1 relates to methods for the identification or authentication of liquid products e.g. a petroleum product by the addition of an anti-Stokes marker. The method includes adding an anti-Stokes luminescent marker compound to the liquid followed by exposing the compound to a light source of a known wavelength or known wavelengths and then detecting one or more shorter wavelength emissions from the marker, where the identity of the liquid is confirmed by the emission wavelength or wavelengths that are detected and quantified.
The detection of dye markers in the above methods requires taking a sample from the petroleum based hydrocarbon products already blended with marker, and followed by analyzing with a suitable laboratory apparatus. Therefore, these methods are so called off-line identification of the marker and generally inconvenient and time consuming. Besides, this approach does not inform the end user at the time of the operation but rather can be used after a complaint.
US2005/0241989 A1 discloses a lubricating oil identification system including a lubricating oil composition containing a passive marker which is detected in situ by a detector installed in an engine. Lubricating oil is filled into the machine comprising a detector and an electronic control unit or machine management chip. Then it is detected whether a passive marker is present in said lubricating oil and the information regarding to the status of the oil passes from the detector to the electronic control unit or machine management chip. The sensor is placed in a machine e.g. the cover of the oil reservoir. Passive markers suitable for the identification system disclosed in US2005/0241989 A1 include microparticles e.g. Radio Frequency Identification (RFID) chips, magnetic tags and biomagnetic tags and molecular species as odourant molecules.
US2007/0064323 A1 discloses a method and a device for the automatic detection of at least one fluorescent and/or light-absorbent indicator contained in a liquid service fluid during the filling of a combustion engine. The detection unit is composed of at least one light source, opto-receiver and measurement section. During the filling of a service fluid into the machine, fluid passes through filler tube which has a measurement section, the light source radiates onto the measurement section when the service fluid flows, and light emanates from the service fluid due to fluorescent effect of an indicator present in it. A measurement signal received form the indicator is evaluated and further utilized to determine automatically the identity of the engine oil. In addition, the number of indicators and their concentrations are considered a multiplicity of encoding options for the engine oils treated with indicator.
Fluorescent organic dyes are popular markers in biotechnology as well. However they have several important limitations. One limitation of organic fluorescent dyes is the absorbance at specific wavelengths. Therefore if a marker is created with a combination of several dyes, excitation at different wavelengths are needed. This limits the number of different dyes that can be used to create different codes since the sensor will require number of different excitation wavelengths which will make the system more complex and increase the cost dramatically. This may not be a dramatic problem in case of an off-line analysis but may be a limiting factor in an on-line analysis. Another limitation of organic dyes is a broad emission profile which causes spectral overlap. This limits the production of large number of optical codes comprised of different dyes. Another limitation of organic dyes is the solubility in hydrocarbon solvents especially for NIR dyes. Photobleaching, luminescence quenching and low extinction coefficient of organic dyes are well known important limitations that impact the analysis time, emission intensity and sensitivity.
Quantum dots (QDOTs) are used in medical and biological applications as markers. Bioconjugates of QDOTs with different active pharmaceutical ingredients have been studied previously. QDOTs are quantum confined semiconductor nanoparticles. QDOTs exhibit luminescence properties when they are excited at a suitable wavelength and exhibit, in part, a size dependent emission wavelength as it is known in the art. QDOTs offer many advantages over traditional organic fluorescent dyes due to their unique properties such as:    1) continuous absorbance and narrow emission band width, which provides minimal spectral overlap of the emission originating from different QDOTs;    2) ability to excite QDOTs emitting at different wavelengths at a single wavelength with a single excitation source, which simplifies the design for the excitation device and reduces the cost;    3) ability to tune emission wavelengths by the size of the semiconductor crystal and/or by the composition of the QDOT in a broad spectral region;    4) large absorbance cross-section and high molar absorptivity of QDOTs which can reduce the detectable level of the emitted light intensity;    5) long luminescent lifetime of QDOTs which allow longer analysis time. QDOTs are investigated as optical codes or tags mainly in the field of biotechnology. First two unique characteristics of QDOTs mentioned above allow the generation of large number of optical codes since the numbers of codes that can be created with fluorescent materials are given as “nm−1” for “m” colors with “n” intensity levels. Also, surface of QDOTs can be functionalized as hydrophilic or hydrophobic to suspend in aqueous or organic (oily) medium. Therefore, QDOTs have a great potential to create a large number of distinct optical codes compared to organic fluorescent dyes and may create signal at much lower doses. Examples include QDOT-doped mesoporous microbeads (S. H. Hu, X. Gao, Advanced Functional Materials, 2010, 20, 3721-3726).
Superparamagnetic nanoparticles are popular class of nanomaterials. These nanoparticles do not possess any net magnetization in the absence of a magnetic field, however they respond strongly to an external magnetic field. If the field is removed, material demagnetizes. Therefore, superparamagnetic nanoparticles, as an example, superparamagnetic iron oxide, known in the art as SPION, is widely used in various fields such as contrast enhancement in MRI, drug delivery, magnetofection, therapy, etc. Magnetic nanoparticles can be dragged to the site of interest with an external magnetic field. This is utilized in many applications such as magnetic drug targeting and magnetofection. Magnetic particles can be captured within a magnetic field and therefore utilized widely in magnetic separation of an analyte, cell, etc. and there are several commercial products and devices for biotechnology utilizing such property.
Microbeads comprised of superparamagnetic nanoparticles and QDOTs are used in the art. European Patent document no. 1 794 764 relates to a method in which magnetic nanoparticles and QDOTs encapsulated in a silica bead and the composition therein.
High performance equipment and machine require high performance fuels, lubricants, coolants and other fluid products to obtain full performance as described and proven by the Original Equipment Manufacturers (OEMs). Fluid products tested during the development process of the equipment/machine for their best performance become integral part of them. In order to guarantee high performance of the equipment/machine during their lifetime and to avoid any issue regarding warranty agreements, it is highly important to utilize working/functional fluids standardized by OEM's.
Each solid component of the equipment/machine has an identification number written on them. If a component fails, this number helps to identify the manufacturer and history of the component with a high accuracy. Even though fluid products are integral part of the equipment/machine, they do not have any identification number. OEMs only release specification to define the fluid products for the equipment or machine and recommend the use of specific working/functional fluids. If there is any issue raised (performance loss, failure, worsening of emissions, warranty etc.) concerning these fluids, there is no reliable technique to trace back the manufacturer and history of the fluid that has been used in the equipment/machine. Therefore, there is an urgent need to give an identification number in the form of tagging material to such working/functional fluids and use a method to determine their identities.
U.S. Pat. No. 6,691,557 B1 discloses a method for analyzing the maintenance status of liquid-filled electric equipment comprising a particle analysis of suspended particles and sediment contained in the liquid.
U.S. Pat. No. 4,649,711 A discloses an apparatus and method for infrared qualitative analysis of a fluid independent of the temperature of the fluid. A first signal is generated in response to detected infrared energy passing through the fluid, and a second datum signal is provided for comparison with the first signal.